Hand-held medical instruments such as dental mirrors have long been known and used the clinical field of dentistry. Dental mirrors allow clinicians to view various parts of the mouth and throat (if used with an extension) that may be difficult or impossible to see by a direct line of sight. However, some parts of the mouth are difficult to see even with the aid of a dental mirror. The lighting conditions inside of a patient's mouth are often poor, at best. A dark dental mirror is often of limited use. Therefore, over the years, the dental industry has sought to develop a mirror with its own illumination system rather than depending on the light available from an overhead lamp. Examples of such mirrors are disclosed in U.S. Pat. No. 3,638,013 to Keller; U.S. Pat. No. 4,279,594 to Rigutto; U.S. Pat. No. 4,629,425 to Detsch; U.S. Pat. No. 4,993,945 to Kimmelman et al.; U.S. Pat. No. 5,139,420 to Walker; U.S. Pat. No. 5,139,421 to Verderber; U.S. Pat. No. 5,457,611 to Verderber; and U.S. Pat. No. 6,443,729 to Watson (hereby incorporated in its entirety by this reference). The most successful of these mirrors have been those which contain a light source built in the handle of the mirror. The mirror disclosed in U.S. Pat. No. 5,457,611 to Verderber is such a device and is the only known illuminated mirror that has been successfully marketed. The Verderber mirror is marketed by Welch-Allyn, Inc., of Skaneateles, N.Y. However, the Verderber mirror splits a light beam in multiple directions, reducing the intensity of light directed to portions of the mouth of interest. Some have also used unsophisticated penlights whereby a traditional mirror or a disposable plastic mirror is clipped on to the penlight. The penlights, however, are similar to basic flashlights, and the plastic clip-on mirrors have poor optical qualities. Therefore, the results have been less than satisfactory.
One of the problems with illuminated mirrors is the heat generated by the illumination source. Prior illuminated mirror handles heat up to uncomfortable temperatures. As a result, the user (e.g., a dental clinician) may have a tendency to put the mirror down repeatedly during clinical procedures. Also, the clinician may be inclined to alternate mirrors during longer procedures to avoid the discomfort. These practices invariably prolong procedures, distract the clinician, and compromise accuracy, all to the potential detriment of the patient.
One solution to the heat problem is proposed in U.S. Pat. No. 5,457,611 to Verderber. Verderber includes a high intensity lamp contained by a heat sink mounted within the dental mirror handle. The handle contains multiple vents spaced from and surrounding the heat sink. Heat from the lamp attempts to radiate through the vents from the heat sink. The radiating heat may create a thermal current, causing heated air to exhaust through the vents and be replaced by cooler air from the surrounding atmosphere (“ambient cooling”). Even with the aid of ambient cooling, the heat generated by the lamp becomes particularly noticeable within five to ten minutes. Handle temperatures for the Verderber mirror reach 134 degrees F., which is uncomfortable and distracting to the clinician.
Another longstanding shortcoming inherent with conventional dental mirrors is the tendency of the reflective surface to become obscured during clinical procedures. Fog, mist, spray from dental drills, tooth debris, dental materials, etc., collect on the mirror's reflective surface, impairing the visibility of the image reflected by the mirror. The need for clear mirrors in dental and otolaryngology offices continues. Procedures ranging from routine hygiene to extensive oral surgeries can benefit from a clear, illuminated mirror.
Currently, clinicians (or an assistant) must repeatedly clean or wipe the reflective surface, which requires repositioning of the mirror and redirection of the clinician's attention, the assistant's attention, or both. This repeated repositioning and redirection of attention, however, can disrupt the concentration of the clinician, leading to reduced accuracy. In addition, mirror-cleaning takes time, and in many cases a patient will benefit from shorter procedure times. In some cases, clinicians or assistants may attempt to wash the mirror with water, but water distorts the image in the mirror and again redirects the attention of the clinician and/or the assistant from the primary function of controlling the operative field.
Another problem with dental mirrors is the susceptibility of the reflective surface to marring by tooth debris, dental materials, or aluminum oxide powder from air-abrasion systems. When such marring occurs, the mirror must be replaced. Replacement mirrors add to the cost of treating a patient. Water flows can be used to clean and protect (to some degree) the reflective surface from abrasion, but the use of water creates at least two new problems. As mentioned above, water distorts of the image reflected by the mirror, and the water must be removed from the patient's mouth.
One other problem associated with dental mirrors is the risk of transmitting germs from one patient to another (i.e., “cross contamination”). Cross contamination may result from handle exposure to multiple patients. Currently, the recommended approach for preventing cross contamination is an autoclave procedure for the mirror handle after each use. However, this approach is time consuming and requires access to and handling of autoclave equipment and materials. The autoclave process increases the wear-and-tear on the mirror handle. Therefore, many clinicians do not follow the recommended approach.
In addition, traditional dental mirrors are not ergonomic. Ergonomics refers to the ease and precision with which instruments can be positioned for control, direction, duration and distance of applied force. When dental clinicians changed posture in the late 1960s from a standing position to a sitting position, the same dental mirrors remained. The angle of the traditional dental mirror surface to the mirror handle is set at approximately thirty-eight degrees. This angle supplies reflected vision for an operator who stands slightly behind, completely behind, or beside a seated patient. However, the standard thirty-eight degree angle is not designed for clinicians sitting in relation to a patient. Dougherty, Dr. Michael: “Ergonomic Principles in the Dental Setting,” DENTAL PRODUCTS REPORT, July 2001, (http://www.dentalproducts.net/xml/display.asp?file=313&bhcp=1).